they were fresh out of a bag at the beginning of class, other students used them though. there was plenty of other stuff to mess with so i doubt anyone bothered to bring or use and of the tools required to reverse polarity.

Seriously. SERIOUSLY PEOPLE.
It's possible to reverse the polarity of a magnet. That is a thing that can be done. These magnets aren't 'broken', they aren't mislabeled, half of them have had their polarity reversed.